Have two 7 month old fillies in a pen. They have good grass hay and good water. Get grain twice a day. One is perfect, the other is slower to come up for grain and you can tell it is hard for her to put her head down to eat. Had a runny nose a month ago so treated with penicillin and nose cleaned up fairly well but is still stiffer and doesn't feel 100% Think it is more than just a common cold so going to have vet out. Any ideas what it could be?